Bug 1188620 - Use PersistentRooted for asyncActivation roots; r=fitzgen

--HG--
extra : rebase_source : 9b568b6b35b9090efaf1f10ba473cfee2db298ab

js/src/gc/RootMarking.cpp

@@ -320,12 +320,6 @@ js::gc::GCRuntime::markRuntime(JSTracer* trc, TraceOrMarkRuntime traceOrMark)
         MarkPersistentRootedChains(trc);
     }
 
-    if (rt->asyncStackForNewActivations)
-        TraceRoot(trc, &rt->asyncStackForNewActivations, "asyncStackForNewActivations");
-
-    if (rt->asyncCauseForNewActivations)
-        TraceRoot(trc, &rt->asyncCauseForNewActivations, "asyncCauseForNewActivations");
-
     if (rt->scriptAndCountsVector) {
         ScriptAndCountsVector& vec = *rt->scriptAndCountsVector;
         for (size_t i = 0; i < vec.length(); i++)

js/src/vm/Runtime.cpp

@@ -135,8 +135,8 @@ JSRuntime::JSRuntime(JSRuntime* parentRuntime)
     profilerSampleBufferGen_(0),
     profilerSampleBufferLapCount_(1),
     asmJSActivationStack_(nullptr),
-    asyncStackForNewActivations(nullptr),
-    asyncCauseForNewActivations(nullptr),
+    asyncStackForNewActivations(this),
+    asyncCauseForNewActivations(this),
     asyncCallIsExplicit(false),
     entryMonitor(nullptr),
     parentRuntime(parentRuntime),

js/src/vm/Runtime.h

@@ -691,12 +691,12 @@ struct JSRuntime : public JS::shadow::Runtime,
      * New activations will reset this to nullptr on construction after getting
      * the current value, and will restore the previous value on destruction.
      */
-    js::SavedFrame* asyncStackForNewActivations;
+    JS::PersistentRooted<js::SavedFrame*> asyncStackForNewActivations;
 
     /*
      * Value of asyncCause to be attached to asyncStackForNewActivations.
      */
-    JSString* asyncCauseForNewActivations;
+    JS::PersistentRooted<JSString*> asyncCauseForNewActivations;
 
     /*
      * True if the async call was explicitly requested, e.g. via